Phaedrus … had noticed again and again … that what might seem to be the hardest part of scientific work, thinking of the hypotheses, was invariably the easiest … As he was testing hypothesis number one by experimental method a flood of other hypotheses would come to mind … At first he found it amusing. He coined a law intended to have the humour of a Parkinson's law that ‘The number of rational hypotheses that can explain any given phenomenon is infinite’. It pleased him never to run out of hypotheses … It was only months after he had coined the law that he began to have some doubts about the benefits of it … If the purpose of scientific method is to select from among a multitude of hypotheses, and if the number of hypotheses grows faster than experimental method can handle, then it is clear that all hypotheses can never be tested …